Air New Zealand says about 10,000 passengers were affected by Sunday's widespread meltdown of a major computer system.
Management worked with operational staff to help alleviate major backlogs at airports after the airline's passenger check-in kiosks, call centre systems and online bookings failed at 9am.
The kiosks came back online at about 3.30pm.
But scores of passengers still had to be cleared across the country, as delayed flights coincided with the end of the school holidays.
The company's short haul airlines manager Bruce Parton describes the situation as a "full-blown system meltdown", never seen before.
He says computer company IBM's performance has fallen well short of expectation.
Air New Zealand introduced the self-check machines last November, at a cost of $30 million.
Mr Parton says at this stage Air New Zealand does not know what caused the disruption, and the company will address that with IBM on Monday.
Mr Parton says Air New Zealand was focusing on ensuring customers got their flights on Sunday and supporting the organisation's operational staff based at the airports.
IBM says the problem was a back-up generator at its Newton Data Centre in Auckland which experienced power failure.
It says one system was badly affected, and 32 technicians have been working to resolve the systems issues.
The two companies will meet on Monday morning to discuss the malfunction.